The field of the invention is human immunodeficiency virus vaccines and immunotherapeutics.
Human immunodeficiency virus is the etiological agent of acquired immune deficiency syndrome (AIDS). The env gene of HIV encodes a 160 kD glycoprotein that is subsequently cleaved into two smaller species, an extracellular (or surface) protein gp120 and a transmembrane protein gp41 (Allan et al., 1985, Science 228:1091; Di'Marzo-Veronese et al., 1985, Science 229:1402). Gp120 is noncovalently linked to gp41 (Allan et al., 1985, Science 228:1091; Chou et al., 1988, J. Infect. Dis. 157:805; Di'Marzo-Veronese et al., 1985, Science 229:1402; Lasky et al., 1987, Cell 50:975).
Among the various HIV isolates, some sequences are highly conserved and some are variable. Two characteristics of the env glycoprotein are conservation of cysteine residues and of a relatively large number of N-linked carbohydrate sites in HIV-1 isolates. Similar secondary and tertiary structures for the env glycoprotein have been suggested based on the similarity of the sequences of HIV.
The env glycoprotein is heavily glycosylated. The unmodified polypeptide backbone of gp120 (about 480 amino acids) weighs about 55 kD. About one half of the molecular weight of gp120 can be accounted for by attached carbohydrates (Allan et al., 1985, Science 228:1091; Geyer et al., 1988, J. Biol. Chem. 263:11760; Matthews et al., 1987, Proc. Natl. Acad. Sci. USA 84:5424; Mizuochi et al., 1988, Biochem J. 254:599; Robey et al., 1985, Science 228:593). Although gp41 is also a glycoprotein, it is not as heavily glycosylated as gp120 (Di'Marzo-Veronese et al., 1985, Science 229:1402). The oligosaccharides of the gp120/41 complex are generally N-linked with no detectable O-linked sugar residues present (Kozarsky et al., 1989, J. AIDS 2:163; Leonard et al., 1990, J. Biol. Chem. 265:10373). The consensus sequence of the site for N-linked carbohydrate attachment is Asn-X-Ser/Thr, where X is any amino acid except Pro and Asp. HIV-1 molecular clones contain an average of 23-24 potential N-linked carbohydrate attachment sites on gp120 and about 4-7 on gp41. The consensus sites on gp120 are generally glycosylated when the env protein is expressed in chinese hamster ovary (CHO) cells (Leonard et al., 1990, J. Biol. Chem. 265:10373).
CD4 is the host cell receptor for HIV (Dalgleish et al., 1984, Nature 312:763; Klatzmann et al., 1984, Nature 312:767; McDougal et al., 1986, Science 231:382). The CD4-binding domain of HIV has been mapped to the C-terminal region of gp120 (Kowalski et al., 1987, Science 231:1351; Lasky et al., 1987, Cell 50:975), although it is reported that sequences in the N-terminal region of gp120 may also be involved (Syu et al., 1990, Proc. Natl. Acad. Sci. USA 87:3695).
Vaccines and immunotherapeutics comprising native gp120 and gp160 have been proposed.